Stoker control



L. M. PERSONS STOKER CONTROL July 16, 1940.

2 Sheets-Sheet 1 Filed July 3, 1956 L.- M. PERSONS STOKER CONTROL July 16, 1940.

Filed July 3, 1936 2 Sheets-Sheet 2 w M 7 M Hrram/sx Patented July 16, 1940 UNITED STATES PATENT OFFICE STOKER CONTROL ware Application July 3, 1336, Serial No. 883% 11 Claims.

The present invention relates to a mechanism and means for operating the same by a timed control and by a temperature control. In particular, it is applicable to stoker control mechanism including a relay selectively energized by timed or thermostat means for predeterminedly operating the motor of a stoker used with coal furnaces, and the like.

An object of the invention is to provide a motor or other similar mechanism, and two control devices operable to close the motor circuit, with means to render one of them inoperative during operation of the other.

Another object is to provide specifically a stoker control mechanism which includes, :in cooperating relation, both a clock and a thermostatic means for selectively energizing a relay to close a switch to actuate a motor for feeding coal, or the like, to furnaces.

A further object is to provide a motor or other similar mechanism, with a temperature-responsive and a time-actuated means to control the operation of the motor, together with means rendering the temperature-responsive means inoperative during operation of the time-actuated means.

Another object is to provide a stoker control including a low voltage relay for controlling a high voltage line in which a stoker motor is connected. I

Another object is to provide a stoker control which includes both time and thermostat circuits as part of a relay, the thermostat having a biasing heater element associated therewith which is energized by current passing through the time control circuit to prevent closing of the thermostat circuit during or just following the passage of current through the time circuit.

Another object is to provide a novel double cam for use as a part of a time control assemblage.

Another object is to provide a novel double cam, and associated adjustable contact means actuated by the cam for use with a time control mechanism,

Other objects and advantages will appear from the following description, taken in conjunction with the accompanying drawings, wherein Fig. l is a plan view of a stoker line switch mounted as a unit with a time control relay and voltage reducing transformer.

Fig. 2 is a side elevation of the assemblage of Fig. 1.

Fig. 3 is a rear view of the assemblage shown in Fig. 1.

Fig. 4 is a section on the line 4-4 of Fig. 1. Fig. 5 is a section on the line 5-5 of Fig. 1. Fig. 6 is a section on the line 6-6 of Fig. 1.

Fig. 7 is a section on the line l'l of Fig. 1.

Fig. 8 is a section on the line 8-8 of Fig. 1.

Fig. 9 is a plan view of the adjustable cam assemblage used as part of the time control mechanism.

Fig. 10 is a diagrammatic view showing the relation of the stoker, the stoker line switch, the 10 time control relay, and the room thermostat relay.

Fig. 11 is a wiring diagram which discloses in detail the main motor control circuit and the time and thermostat relay circuits which control 1 the opening and closing of a switch in the main stoker motor circuit.

Referring more particularly to the drawings by reference numerals, indicates generally an assemblage which includes as a compact unit a 20 line switch for a stoker motor, or the like, a time controlled relay therefor, and a transformer unit. A room thermostat unit is disposed in a room, or the like, operable by heat changes therein, and is wired into the time relay to cooperate therewith to selectively control the switch, as will be explained hereinafter. A base 2| of non-conducting material supports the various elements of the assemblage.

The line switch 22 is described in detail in my copending application Serial No. 79,053, filed May 11, 1936, Patent No. 2,159,342, May 23, 1939. It includes a plate 23 connected to the base 2| by screws 24, or the like, which supports a pivot block 25 by a pin 26 journaled therein. A contactcarrying member generally indicated 21 having a U-shaped bimetallic element 28 is connected by screws 28, or the like, to the pivot block. The member 21 also has an insulating connecting portion 29 and a switch blade 30 carrying a contact 4 3| which are connected by a screw 32, or the like. The switch blade carries at the end remote from this connection a relatively permeable element 33 which is adapted to move between the legs of a U-shaped permanent magnet 34 connected by a screw 35, or the like, to the base 2|.

A switch plate 38 is supported on a switch backing plate 39 at a fixed connection 40, which also serves as a terminal. The plate 39 is fixed relative to the base 2| by means of the aforesaid screw 35. The switch plate 38 includes a relatively movable portion 4| which carries a contact 42 adapted to cooperate with the contact 3|. There is opposed to the contact-carrying member 21 a member generally indicated 45 5-5 which is of a construction similar thereto, and includes a U-shaped bimetallic element 56 connected-to the pivot block by screws til, or the like; an insulating portion at; and a connecting element Q9. The element 39 is secured in position relative to the base 2! by adjustable nut and pin means 50, or the like, which includes a spring 5!, a nut 52, a pin 53, and spaced fixed washer elements 54. The element 39 is slotted at 59 to allow for longitudinal movement of the member d5 during expansion or contraction of the bimetallic element 66. A heater coil 55 is disposed adjacent the bimetallic element 456 and is connected in series therewith. Leads 56 and 5? serve to connect the heater in a circuit to be hereinafter described. Leads 60 and 6t are adapted to connect the switch in a motor circuit, which will be hereinafter referred to, the lead 5t being connected to the switch blade at the terminal 62, and the lead St to the switch plate 38 at the terminal 40. The heater afiects only the bimetallic element 06, and is insulated from the bimetallic element 28 by the base 2!, this latter element 28 being a compensating thermal member obviating the effect of ambient air temperatures, and is equal and opposite in its action to the element 56.

Also supported by the base 2! is a time control relay mechanism, which includes an electric clock 05 which is connected to the rear of the base M by screws 66, or the like. A shaft 6? is operatively connected to the clock and extends through the base 2|. The shaft 61 makes one full rotation in an hour in a normal timed setting, though this movement may be varied.

An adjustable double cam 69 is fixed to the shaft 0?, and includes one element 69 of a configuration shown in Figs. 1 and 9 in full lines, and a second element ID of a configuration shown in Figs. 1 and 9 in dash lines. The element 69 includes a hub ll having an associated set screw H by means of which it is fixed to the shaft 01 and the element 10 is rotatable about this hub.

The cam elements 69 and 10 are identical in contour, each being provided with the same indenations, although the elements, in place, are turned 180 from a position of coincidence. By thus employing two identical elements, manufacturing expense is reduced. The object of this double cam is to provide for either one or two operations of the cam follower switch, for each revolution of the cam.

The element 69 is provided] with three V-shaped peripheral indentations 69!, E92, and 693, the designations running consecutively clockwise from the larger arcuate portion. The element i0 is provided with three V-shaped indentations ml, 102, and I03, correspondingly designated. The elements are faced. together in such position that the larger arcuate portions are diametrically opposite each other. The element 69 has an arcuate slot I3 therein through which a screw It passes, the screw being threaded into the element 10. This slot is of an arcuate length in degrees equal to the arcuate length of one indentation.

In the position of Fig. 1, the elements are adjusted so that only one indentation is present in the cam. In this position, the indentations 692 and 103 are made to coincide. However, the indentations Gill and 693 are opposite arcuate portions of the element 10, and hence neither is effective. In the position of Fig. 9, two indentations are made to coincide, th'e elementshaving been shifted until the screw 14 engages the opposite end of the slot 13. In this position, the inaaoaeaa dentations 69! and 693 of the element 69 regis ter with the indentations 103 and FM, respectively, of the element 10. These respective pairs of indentations are diametrically opposite, so that two equally spaced operations of the cam follower switch occur during a single revolution of the cam. In either position of operation, the screw it is turned down to maintain the elements together as adjusted.

The cam in its rotation through movement of the shaft fi'l is adapted to make and break the contacts in an associated switch assemblage, generally indicated 35. The switch l5 includes a supporting bracket 16 secured to the base 2! by screws H, or the like, having an upstanding portion 118. The bracket H5 serves as a terminal post for a switch blade, described below. A resilient blade 19 is secured to the upstanding portion 38, and carries at an end remote therefrom a contact 80. A relatively movalble resilient blade @i is fixed to the portion 78 of the bracket, insulated from the blade l9 by means 82, and carries at the end remote therefrom a contact 89 and a V-shaped element 8 2. The contact 83 is adapted to cooperate with the contact 80. A rigid supporting arm 85 is fixed at one end to the upstanding portion 78 of the bracket in insulating relation to the blades 19 and 8! by insulating means 86, and carries at its other end a screw adjustment Bl which is adapted to selectively position the blade l9 relative to the arm 85 and, therefore, to the blade 8i. Screws 86', or the like, maintain the blades 79 and 8!, and the arm 85 fixed to the portion 18. The adjustment includes an internally threaded sleeve 88 fixed relative to the arm 95; a screw 89 threadedly engaged in the sleeve having a head 90 at one end and a serrated wheel 9| fixed to the other end; anda detent 92 fixed to the arm and serving to maintain the wheel 9| in selected position. The blades is and 0| have slots 95 and 96, respectively, therein through which the screw 89 extends. The head abuts the remote side of the blade 19 at the slot' 95, in a manner to draw the said blade towards the arm 85, whereas the blade 8| has free movement relative to the screw 89.

It is thus apparent that rotation of the wheel 9| serves to move the blade 79 towards the arm 85 and therefore towards the blade 8 l, movement of-the blade in the opposite direction being effected by the above noted inherent resiliency of Likewise supported upon the base 2! is a transformer unit 98, the details of which are not shown, inasmuch as they form, per se, no particular part of the present invention. The transformer is held in place against the rear portion of the plate 2| by means of a U-strap 99 which is fixed to the base by screws I00, or the like. This transformer reduces the line voltage.

The details of the room thermostat are not disclosed, inasmuch as they also form no part of the present invention as such; but a type similar to that disclosed in my copending application Serial No. 80,990, filed May 21, 1936, Patent No. 2,145,950, Feb. 7, 1939, may be employed.

In Fig. 11, there is diagrammatically shown the electrical interrelation between the stoker motor,

2,207,942 circuit from the main line through the primary of the transformer and the circuit from the main line through the stoker motor and its line switch are in parallel. Likewise, the thermostat control circuit and the time control circuit, which constitute selectively operated relays to close the line switch, are in parallel. The circuits are traced as follows:

' The two main power lines are I05 and I09, the former being connected to the terminal post I43, and the latter to the post I42. Connected directly across the line from these two terminals is the primary I01 of the transformer, the circuit being as follows: terminal I43, lead I08, primary I01, line II3, terminal I40, line H2, and terminal I42. The stoker motor H is likewise connected in parallel with the primary across the terminals I43 and I42, and in series with it is the switch 22. This circuit is traced as follows: terminal I43, lead 6|, terminal 40, fixed contact 42, movable contact 3|, terminal 62, lead 60, terminal I4I, motor IIO, terminal I40, line H2, and terminal I42. Thus, when the terminals I43 and I 42 are connected to a power source, and the stoker motor connected to terminals I40 and I M, the primary I0 I will be immediately energized, and the motor energizable upon closure of the switch 22.

The secondary circuits will now be explained. The secondary I I5 of the transformer is connected at opposite ends to the inner terminals I I1 and I28 of the mechanism. Constantly across these terminals is placed the electric clock mechanism, the same having terminals I60 and I 6I The circuit is as follows: secondary terminal II'I, lead I50, clock terminal I60 through the clock, clock terminal I6I, line I5I, and terminal I28. Since this circuit is always closed, there will always be a current flowing through the secondary Il5.

Two additional secondary circuits, namely, the room thermostat circuit and the timed circuit, are connected in parallel with each other and with the clock, across the secondary. The room thermostat circuit is as follows: terminal 1, line 56, terminal 56, bimetallic element 46, heater 55, lead II8, terminal I46, lead I26 to the room thermostat, contact I21, thermostat switch I25, terminal I51, line I52, terminal I45, line I20 to terminal I28. Thus, it will be seen that the room thermostat is connected across the terminals I45 and I46 of the device, and that, when it is closed, the heater 55 will be energized.

The timed circuit is traced as follows: terminal I", lead 56, contact 56, bimetallic element 46, heater 55, lead II8, terminal I46, lead II6, terminal I6, relatively fixed blade 19, contact 80. contact 83, movable blade 0|, terminal 8I', line I22, terminal I44, line I48, biasing heater I2I, line I54, terminal I51, line I52, terminal I45, line I20, and terminal I28. Thus, the biasing heater from the room thermostat is connected across terminals I44 and I45, and will be energized when the clock-controlled switch is closed.

Thus, it is apparent that there has been provided a multiple control heat relay for controlling the motor of a furnace stoker. The above referred tobiasing heater I2I is disposed in heatsupplying relation to he thermally-sensitive element of the room thermostat, and is connected in series with the circuit controlled by the clock mechanism. It is used to prevent the room thermostat from calling for firing action on the part of the stoker immediately after the stoker has been actuated by the time mechanism, as would dropped to the closing temperature of the room thermostat before the heat resultant of a load of coal supplied by .the time mechanism could be carried to the room. The biasing heater raises the temperature of the switch during the energization of the time-controlled circuit, and keeps it from closing.

The use of the transformer 98 in the switch assemblage provides a means for securing a low voltage for the relay circuits and the biasing heater, which is an important feature of the invention.

It is, of course, obvious that energization of the heater element 55 produces heat to close the main line switch, no matter which relay circuit functions.

Operation It is now apparent that the present invention contemplates controlling a stoker to prevent a coal fire from going out, even when the room temperature stays for along period of time above that temperature which would normally close the room thermostat to actuate the stoker. It provides a time control relay which is adapted to cause the stoker to feed a supply of coal to the furnace once or twice every hour, depending upon the setting of the cam 68.

In using the device, the first adjustment is that of the cam. By loosening the screw 14, the element 10 is rotated relative to the element 69 to determine whether, as in Fig. 1, one notch is present, or, as in Fig. 9, two notches are present. Or, in other words, this cam is adjusted to determine whether one or two charges of coal shall be made every hour.

Next, the switch is adjusted. The total arcuate extent of each cam notch may be about fifteen minutes, or one quarter of a revolution. It will be assumed that the switch is closed, the follower 84 being at the bottom of the V-notch, as shown in Figs. 1 and 9. Rotation of the cam moves the follower radially outward and ultimately breaks the contacts 80 and 83. Since a certain amount of this radial movement is required to produce a clear break in the contacts, a maximum of only about half the arcuate extent of the cam notch is available during which the switch is closed. The cam is rotated from this starting point until the lapse of one-half the time desired for operation of the stoker motor and, at this point, the wheel 9| is rotated until any further rotation of the cam will break the contacts. Thus, any desired time of operation of the stoker motor may be obtained by proper adjustment of the wheel 9|.

With the device thus adjusted, the power lines connected to terminals I42 and I43, the motor connected to terminals I and I, the room thermostat connected to terminals I45 and'I46, and the biasing heater connected to terminals I44 and I45, the apparatus operates as follows: The primary I 01 is excited, and causes excitation of the secondary, which, in turn, operates the clock. These circuits constantly remain thus.

After a certain time interval, the cam 63 will operate to close the switch I5, and the secondary circuit through it, the biasing heater I2I, and the relay heater will be energized. The relay heater 55 acts on the bimetal 45 to close the contact points 3I and 42 of the line switch 21, which completes the main line circuit through the motor IIII of the stoker. Simultaneously, the biasing heater I2I is excited to generate heat which maintains the bimetallic element of the thermostat switch I25 in open position so that the therduration of this operation of the stoker by this time control is determined by the adjustment of the switch 15 by the wheel-9|.

Should the room cool, the room thermostatmay operate the stoker as follows: When the contacts I21 and I of the room thermostat close at drop of the temperature in the room, the thermostat relay is closed, and the heater 55 is energized to produce heat, which affects the bimetallic element 46 to close the contact points 3| and 42 of the line switch, thereby completing the stoker motor circuit to energize the motor, which actuates the stoker mechanism to flre the furnace. This circuit, of course, cannot operate if the thermostat is held open by heat from the biasing heater.

Inasmuch as the circuits, both main and relay, are traced in the detailed description of the device, they have not been retraced in the discussion of the operation of 'the device.

From the above description, considered with the accompanying drawings, it is apparent that there has been provided a novel automatic stoker conposed, the cam may be provided with either one trol mechanism adapted to fulfill all of the objects and advantages enumerated and suggested.

It is to be understood that the above description and the accompanying drawings are given by way of illustration and example and not for limitation, the invention being limited only by the following claims.

What is claimed is:

1. In a device of the kind described, a thermally-sensitive switch, a thermostat-controlled circuit to operate the switch, and a time-controlled circuit to operate the switch, said latter circuit having in series therewith a biasing heater element which is disposed in heat-giving relation to the thermostat to prevent the thermostat from closing for a predetermined time after energization of the time-controlled circuit.

2. In a device of the kind described, a stoker motor, a switch in series therewith, a thermostat-controlled circuit to operate the switch, and a time-controlled circuit to operate the switch, said latter circuit including in series therewith a biasing heater which is disposed in heat-giving relation to the thermostat to prevent it from closing for apredetermined time after energize.- tion of the time-controlled circuit.

3. In a device of the kind described, a cam comprising two elements identical in peripheral contour, and a plurality of indentations on each contour, said indentations being so designed that when said elements are superposed, the cam may be provided with either one or a plurality of indentations by rotation of one element relative to the other, and means for maintaining the elements in adjusted position.

4. In a device of the kind described, a circular ca-m comprising two elements identical in peripheral contour, and a plurality of indentations on each contour, said indentations being so designed that when-said elements are superor a plurality of equally spaced indentations by rotation of oneelement relative to the other.-

aaoaeea 5; In a device of the kind described, a stoker motor and a switch in series in a high voltage line, a thermostat-controlled circuit and a timecontrolled circuit to selectively operate the switch, a heater element in the latter circuit dis- 5 posed to prevent operation of the thermostat Just following energization of the time-controlled circuit, and means in'pa-rallel with the motor to step down the line voltage to supply low voltage for the circuits. 1

6. In a device of the kind described, a line circuit, a motor and a thermally-sensitive switch in series in the said circuit, a thermostat-controlled circuit and a time-controlled circuit to selective- 1y operate the switch, said circuits being in par- 1 allel, a heater element in the time-controlled circuit disposed to prevent operation of the thermostat during or just following energization of the time controlled circuit, and means to take high voltage current from the line and to supply low voltage current to the circuits.

'7. In a mechanism of the kind described, a main circuit, two control circuits including a time actuated circuit and a thermally actuated circuit each adapted to energize or deenergize the main circuit, time means actuating said timecontrolled circuit for a predetermined interval of time to operate said main circuit during said interval, and means put into operation by actuation of said time actuated circuit and acting ;;2 upon the thermally actuated control circuit to render said latter control circuit inoperative to energize the main circuit for a predetermined period of time after the interval of actuation of the main circuit by said former control circuit.

8. In a mechanism for use with a furnace having an electrically operated device for causing the furnace to be heated, a time operatedcontrol circuit for putting said device into operation, a thermostat and a thermal control circuit for putting said device into operation, and a heater in the time operated circuit energized upon actuation of the said circuit, said heater being positioned adjacent the thermostat to prevent closing of the same when the time operated circui is being actuated.

9. A stoker control including a motor, a circuit therefor and a time controlled switch in said circuit, said switch including a clock mechanism, a shaft rotated thereby, a pair of identical round elements one of which is adjustably secured to the shaft, each element having a plurality of vnotches in its periphery, two such notches being diametrically opposed and the third being adjacent one of the two, all of said notches subtending chords of the element equal to its radius, said two elements being superposed and the one being adjustable-through sixty degrees over the other in such wise as to provide a cam having selectively one notch or two opposite notches, a follower, a contact thereon, means urging said follower-against the cam, a switch blade adjacent the follower, and a second contact on the blade, said blade being adjustably maintained in a given position relative to'the follower, whereby the depth the follower extends into the notches determines the closing of the contacts. and the adjustment of the blade determines the period of time the contacts are closed, and consequently the period of operation of the stoker motor. 7 10. In a system of the kind described, a heat change producing device to be controlled, a circuit and a time-operated means in said circuit for controlling the device and causing periodical operation thereof, a circuit and a temperature responsive means in said circuit for controlling the device in response to temperature changes resulting from the heat change device, said lastnamed circuit being normally free of said timeoperated means and adapted to operate continuously upon demand at the thermostat, and means rendered effective upon operation of the timeoperated means to prevent operation oi the temperature responsive means to close the circuit until an interval has elapsed after completion of operation of the time-operated means, whereby the heat'change device may influence the temperature responsive device in accordance with its said operation by the time-controlled means.

11. In a system of the kind described, a heat change producing device to be controlled, a temperature responsive circuit including a thermostat subject to heat changes produced by the heat change producing device for effecting said control, a clock, an independent time-controlled circuit for additionally'efiecting said control, the temperature responsive circuit being normally free of the time-controlled circuit and adapted to operate continuously upon demand at the thermostat, said time-controlled circuit having in series a switch operated for a predetermined interval of time by the clock and a means to influence the temperature controlled circuit to prevent operation thereof for an interval after the interval of operation of the heat change producing device by the time-controlled circuit. LAWRENCE M. PERSONS. 

